Emergent Edge Modes in Shifted Quasi-One-Dimensional Charge Density Waves

Area of Science:

• Condensed Matter Physics
• Materials Science
• Topological Physics

Background:

• Charge density waves (CDW) are collective electronic states found in low-dimensional materials.
• Topological phases of matter exhibit robust edge states protected by topology.
• Understanding novel topological phases is crucial for next-generation electronic devices.

Purpose of the Study:

• To propose and investigate a novel two-dimensional (2D) phase of charge density waves (CDW).
• To characterize the topological properties and edge modes of this proposed 2D CDW phase.
• To explore the stability and experimental feasibility of these predicted phenomena.

Main Methods:

• Theoretical modeling of a 2D CDW phase constructed from coupled 1D CDW wires with phase shifts.
• Calculation of topological invariants (Chern number) for the bulk CDW phase.
• Analysis of edge mode properties, including spectral flow and stability against interwire coupling.

Main Results:

• The proposed 2D CDW phase possesses a fully gapped bulk and exhibits topological properties characterized by a nonzero Chern number.
• Topological edge modes are predicted to exist within the bulk gap.
• These edge modes display spectral pseudoflow as a function of position, a phenomenon dual to momentum-space spectral flow in Chern insulators.
• The CDW edge modes are shown to be stable against interwire coupling.

Conclusions:

• A novel 2D topological phase of charge density waves is theoretically proposed.
• The unique spectral pseudoflow of CDW edge modes offers a new platform for studying topological phenomena.
• Experimental verification is possible in quasi-1D CDW materials like Ta2Se8I.